Chemoenzymatic Synthesis of N-glycan Positional Isomers and Evidence for Branch Selective Binding by Monoclonal Antibodies and Human C-type Lectin Receptors

ACS Chem Biol. 2018 Aug 17;13(8):2269-2279. doi: 10.1021/acschembio.8b00431. Epub 2018 Jun 21.


Here, we describe a strategy for the rapid preparation of pure positional isomers of complex N-glycans to complement an existing array comprising a larger number of N-glycans and smaller glycan structures. The expanded array was then employed to study context-dependent binding of structural glycan fragments by monoclonal antibodies and C-type lectins. A partial enzymatic elongation of semiprotected core structures was combined with the protecting-group-aided separation of positional isomers by preparative HPLC. This methodology, which avoids the laborious chemical differentiation of antennae, was employed for the preparation of eight biantennary N-glycans with Galβ1,4GlcNAc (LN), GalNAcβ1,4GlcNAc (LDN), and GalNAcβ1,4[Fucα1,3]GlcNAc (LDNF) motifs presented on either one or both antennae. Screening of the binding specificities of three anti-LeX monoclonal IgM antibodies raised against S. mansoni glycans and three C-type lectin receptors of the innate immune system, namely DC-SIGN, DC-SIGNR, and LSECtin, revealed a surprising context-dependent fine specificity for the recognition of the glycan motifs. Moreover, we observed a striking selection of one individual positional isomer over the other by the C-type lectins tested, underscoring the biological relevance of the structural context of glycan elements in molecular recognition.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Monoclonal / metabolism*
  • Biocatalysis
  • Cell Adhesion Molecules / metabolism
  • Humans
  • Isomerism
  • Lectins, C-Type / metabolism*
  • Mice
  • Polysaccharides / chemistry*
  • Polysaccharides / metabolism*
  • Receptors, Cell Surface / metabolism
  • Receptors, Mitogen / metabolism


  • Antibodies, Monoclonal
  • CLEC4G protein, human
  • CLEC4M protein, human
  • Cell Adhesion Molecules
  • DC-specific ICAM-3 grabbing nonintegrin
  • Lectins, C-Type
  • Polysaccharides
  • Receptors, Cell Surface
  • Receptors, Mitogen